Structs in the Apache OpenOffice API are used to create compounds of other UNO types. They correspond to C structs or Java classes consisting of public member variables only.
While structs do not encapsulate data, they are easier to transport as a whole, instead of marshaling get() and set() calls back and forth. In particular, this has advantages for remote communication.

You gain access to struct members through the . (dot) operator as in

aProperty.Name="ReadOnly";

In Java, C++ and Apache OpenOffice Basic, the keyword new instantiates structs. In OLE automation, use com.sun.star.reflection.CoreReflection to get a UNO struct. Do not use the service manager to create structs.